Safety lock for semitrailers



July 18, 1944. D. E. BRAMBLE ,3

SAFETY LOCK FOR SEMITRAILERS I Filed April 2', 1943 4 Sheets-Sheet l I urn/fur July 18, 1944. D. E. BRAMBLE SAFETY LOCK FOR SEMITRAILERS 4 Sheets-Sheet 2 Filed April 2, 1943 Inventor ,wmzdzvwrwzz "4 and July 18,1944. 3 D. E.IBRAMB LE 3 3-9 SAFETY 'LOCK FOR SEMI'I'RAILERS Filed April 2, 1943 4 Sheets-Sheet .3

Inventor July 18, 1944. D, BRAMBLE 2,353,992

SAFETY LOCK FOR- SEMI'ITRAILERS Filed April 2, 1945 4-Sheets-Sheet 4 Inventor Patented July 18, 1944 UNITED STATES PATENT- OFFICE 2,353,992 i Y SAFETY LocK FOR SEMITRAILERS Donald Earl Bramble, Chicago, 111.- Application April 2, 1943, Serial No. 481,619

(c1. 2s0-s3.1)

3 Claims.

The present invention relates to new and useful improvements in semi-trailers, and has for its primary object to provide, in a manner as hereinafter set forth, novel means for automatically locking .the trailer to the tractor when the usual landing gear of the former is raised to inoperative position, thereby positively preventing separation of the two until said landing gear is again lowered. Y

Other objects of the invention are to provide an automatic safety lock of the aforementioned character for semi-trailers which will be comparatively simple in construction, strong, durable, highly efficient and reliable in use, compact, light in weight, and which may be manufactured and installed at low cost.

All of the foregoing and still further objects and advantages of the invention will become apparent from a study of the following specification, taken in connection with the accompanying drawings wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Figure 1 is a perspective view, showing an embodiment of the invention installed foroperation on a semi-trailer equipped with a landin gear of the swinging type. i

Figure2 is a view in vertical longitudinal section through,v the front portion or nose of the semi-trailer.

Figure 3 is a cross-sectional view, taken substantially on the line 3--3 of Figure 2.

Figure 4 is a view in side elevation of an embodiment of the invention which is for installation on semi-trailers which are equipped with landing gears of the vertically movable type, the shaft of the safety lock being shown in crosssection.

Figure 5 is across-sectional view, taken substantially on the line 5-5 of Figure 4.

Figure 6 is a perspective view of the pivoted lever-supporting frame.

Figure '7 is a detail view in perspective of the lever.

Referring now to the drawings in detail, and to Figures 1, 2 and 3 thereof in particular, it will be seen that reference numeral l designates a metallic arm which is welded longitudinally on the pivoted end portion of the usual leg 2 of a conventional semi-trailer landing gear 3 of the swinging type. A forwardly extending metallic rod 4 is pivotally and adjustably secured at its rear end, as at 5, to the free end portion of the arm I. A depending guide 6 is provided for the rod 4 on one of the frame members I of the semitrailer 8. v

A transverse shaft 9. is journaledin openings which are provided therefor in thelongitudinal frame members III of the semi-trailer 8 above the fifth wheel plate I l of said semi-trailer and forwardly of the kingpin ,l2. An arm I3 is fixed onone end portion of the shaft 9, to, which arm the forward end of the rod v4 is pivotally connected- A dog Misfixed omtheshaft 9 at an intermediate point. r The dog [4 is operable in av longitudinal slot I5 which is provided therefor in the fifth wheel plate ll forwardly of the king pin [2. I

The dog I4 is also. operable between a pair of angular brackets 16 (see Fig. 3) which are welded on the fifth wheel plate II on oppositesides of the slot l5. The shaft 9 is journaled in openings which are provided therefor in the brackets IS. A bar ll of angle iron is welded transversely on the fifth wheel plate II at the forward end of .the slot I5 for supporting th dog Hi When it is in operative position. I It is thought that the operation of thedevice willbe readily apparent from a consideration of the foregoing. Briefly, when the landing gear 3 is in lowered position, the dog i4 is in raised or inoperative position, as illustrated in dotted lines in Figures 1 and 210i .thedrawings. Thus, the tractor may be connected to or disconnected from the semi-trailer in the usual manner. When the tractor has been connected to the semi-trailer and the landing gear 3 is swung upwardly, the members I, 4 and I3 rock the shaft in a direction to swing the dog 14 downwardly to a substantially vertical position through the slot [5 into abutting engagement with the bar [1, thereby positioning the lower end portion of said dog in the forward path of the fifth wheel l8 of the tractor. It will thus be seen that the tractor cannot pull away from the semi-trailer so long as the landing gear 3 is in raised or inoperative position. The device also functions as a safety lock in the event of failure of the usual fifth wheel lock of the tractor.

In the embodiment illustrated in Figures 4 to 6, inclusive, of the drawings, a depending plate I9 is fixed beneath the frame structure of the semi-trailer adjacent the vertically movable landing gear 20 of said semi-trailer. Mounted on the plate [9 is a pair of brackets 2|. The brackets 2| support a frame 22.

A lever 23 is pivotally mounted, at an intermediate point, in the upper front portion of the frame 22 for swinging movement in a vertical plane. The lever 23 includes a substantially rounded end portion to which one end of the dog-operating rod 4 is pivotally connected, as at 24. A return spring 25 is connected to the other end portion of the lever 23. A vertical bar 26 is mounted on the axle 21 of the landing gear 20. The upper end portion of the bar 26 is slidable in the frame 22 for engagement with the lever 23 for actuating said lever against the tension of the spring 25. In other respects the construction of this form of the invention is substantially similar to the embodiment illustrated in Figures 1, 2 and 3 of the drawings.

In operation, when the landing gear is raised, the upper portion of the vertical bar 26, traveling in the frame 22, engagesand rides on the rounded end portion 28 of the lever 23, thereby swinging said lever in a direction, against the tension of the spring 25, to move the rod 4 forwardly, thus swinging the dog l4 downwardly to operative position, as seenlin dottedlines in Figure 4 of the drawings. When the landing gear 20 is lowered, the bar 25 drops therewith and the spring 25 actuates the lever 23 for returning the dog [4 to raised or inoperative position. In addition to supporting the lever 23; the frame 22 functions as a guide for the bar 26 It is believed that the many advantages of an automatic safety lock for semi-trailers constructedin accordance with thepresenti-nvention will be readily understood, and although preferred embodiments of the device are as illustrated and described, it is to be understood that further modifications and changes in the details of construction may be resorted to which will fall within the scope of the invention as claimed.

What is claimed is:

1. An automatic safety lock for semi-trailers of the type having a retractible landing gear, a fifth wheel plate and a depending king pin engageable with the fifth wheel of a tractor, com-' prising a pair of brackets mounted on the fifth wheel plate, said fifth wheel plate having a 1ongitudinal slot therein between the brackets and forwardly of the king pin, a transverse shaft journaled in the brackets and-in the frame structure of the semi-trailer, a' transverse bar fixed on the fifth'wheel plate at the forward end of the slot, a dogfixed' onthe shaft between the-brackets and operable, for forward movement, in the slot for positioning in front of the fifth wheel of the tractor for engagement therewith for preventing separation of said tractor from the semitrailer, said dog, when in operative position, being engageable with the bar to provide a reinforcing stop for the dog, and means operatively connecting the shaft to the landing gear for forwardly swinging the dog to operative position when said landing gear is moved to inoperative position.

2. A safety lock for semi-trailers having a swinging landing gear, a fifth wheel plate and a king pin depending therefrom for connection Withthe fifth wheel of a tractor, said fifth wheel plate having a longitudinal slot therein forwardly of the king pin, said safety lock comprising an upstanding arm fixed on the pivoted end portion of the landing gear, a transverse shaft journaled on the trailer above the fifth wheel plate and forwardly of the king pin, a dog fixed on the shaft and operable in: the slot for forward movement and. engagement with the tractor fifth wheel, a stop at the front end of the slot and engageable by the dog to limit forward movement of the dog, an arm fixed on the shaft, and a rod connecting the second-named arm to the first-named arm for rocking the shaft for swinging the dog to operative position when the landing. gear is retracted.

3; A safety lock for trailers having a vertically movable landing gear, a fifth wheel plate having a longitudinal slot therein and a king pin depending from said plate rearwardly of the slot, said safety lock comprising a frame mounted on the semi-trailer adjacent the landing gear, a, lever'pivotally mounted on said frame, a transverse shaft journaled on the semi-trailer above the fifth wheel plate and forwardly of the king pin, a dog fixed on said shaft and operable in the slot for engagement with a fifth wheel of a tractor and arranged for forward and backward movement, a rod operatively connecting the lever to the shaft for swinging the dog to operative position, and a bar on the landing gear for movement therewith, said lever being in the path of retracting movement of the landing gear to actuate the dog into its locking position.

DONALD EARL BRAMBLE. 

